Elevated blood pressure (a.k.a. hypertension) is a major risk factor for cardiovascular disease. As a result, blood pressure measurement is a routine task in many medical examinations. Timely detection of hypertension can help inhibit related cardiovascular damage via accomplishment of effective efforts in treating and/or controlling the subject's hypertension.
A person's blood pressure is a continuously changing vital parameter. As a result, sporadic office blood pressure measurements may be insufficient to detect some forms of hypertension. For example, hypertension can occur in a pattern that evades detection via isolated office blood pressure measurement. Common hypertension patterns include white coat hypertension (elevated only during a limited morning period of time), borderline hypertension (fluctuating above and below definitional levels over time), nocturnal hypertension (elevated only during sleeping hours), isolated systolic hypertension (elevated systolic pressure with non-elevated diastolic pressure), and isolated diastolic hypertension (elevated diastolic pressure with non-elevated systolic pressure). To detect such hypertension patterns, it may be necessary to perform additional blood pressure measurements over time to obtain a more complete view of a person's blood pressure characteristics. Although continuous measurement of blood pressure can be achieved by invasive means, for example, via an intra-arterial pressure sensing catheter, noninvasive blood pressure measurement approaches are more typically used.
Current noninvasive blood pressure measurement approaches include ambulatory and home blood pressure measurement strategies. These strategies provide such a more complete view of a person's blood pressure characteristics and are often employed in recommended situations. Ambulatory blood pressure measurement is performed while the person performs daily life activities. Currently, ambulatory blood pressure measurements are typically performed every 20 to 30 minutes using brachial oscillometric blood pressure measurement cuffs. Ambulatory blood pressure measurement may be recommended where the is large variability in office blood pressure measurements, where a high office blood pressure measurement is made in a person with otherwise low cardiovascular risk, when office and home blood pressure measurements vary, where resistance to drug treatment of blood pressure is noted or suspected, where hypotensive episodes are suspected, or where pre-clampsia is suspected in pregnant women. Home blood pressure measurement include isolated self-measurements performed by a person at home. Home blood pressure measurements may be recommended where information is desired regarding the effectiveness of blood pressure lowering medication over one or more dose-to-dose intervals and/or where doubt exists as to the reliability of ambulatory blood pressure measurement.
Current ambulatory and home blood pressure measurement approaches, however, fail to provide continuous measurement of blood pressure. Additionally, when an oscillometric blood pressure measurement cuff is used to monitor a person's blood pressure when sleeping, the intermittent inflation and deflation of the cuff can disturb the person's sleeping pattern, thereby harming the subject to some extent and potentially changing the person's sleeping blood pressure. Thus, convenient and effective approaches for noninvasive continuous measurement of blood pressure remain of interest.